In this paper, a novel distortion model based on a mixture of Laplacian distributions is presented for the transform
coefficients of predicted residues in quadtree coding. The mixture Laplacian distribution is made on the coding structure
with different quadtree coding unit (CU) depth. Moreover, for intra-coded CU, the distortion model is asymptotically
simplified based on the signal characteristics of the transform coefficient. The proposed mixture model of multiple
Laplacian distributions is tested for the High Efficiency Video Coding (HEVC) Test Model (HM) with quadtreestructured
Coding Unit (CU) and Transform Unit (TU). The experimental results show that the proposed model achieves
more accurate results of distortion estimation than the single probability models.
In this paper, 16-order and 32-order integer transform kernels are designed for the HD video coding in
H.264|MPEG-4 AVC and the performance analyses for large transforms are presented. An adaptive block size transform
coding scheme is also proposed based on the proposed transform kernels. Thus, additional 16-order (16 × 16, 16 × 8 and
8×16) and 32-order (32×32, 32×16 and 16×32) transforms are performed in addition to 8×8 and 4×4 transforms
which are exploited in the Fidelity Range Extension of H.264|MPEG-4 AVC. The experimental results show that the
variable block size transforms with the proposed higher order transform kernels yields 14.96% of bit saving in maximum
for HD video sequences.
We introduce an efficient mode selection method in the enhancement layers of spatial scalability in the SVC encoder by selectively performing the inter-layer residual coding of the SVC. The proposed method is to make an analysis of the characteristics of integer transform coefficients for the subtracted signals for two residuals from lower and upper spatial layers. Then it selectively performs the inter-layer residual prediction coding in the spatial scalability if the SAD values of inter-layer residuals exceed adaptive threshold values. Therefore, by classifying the residuals according to
the properties of integer-transform coefficients only with the SAD of inter-layer residual signals between two layers, the SVC encoder can perform the inter-layer residual coding selectively, thus significantly reducing the total encoding time with 51.2% in average while maintaining the RD performance with negligible amounts of quality degradation.
In this paper, a fast intermode decision scheme which is suitable for the hierarchical B-picture structure in which much computational power is spent for combined variable block sizes and bi-predictive motion estimation is introduced. The hypothesis testing considering the characteristics of the hierarchical B-picture structure in the proposed method is performed on 16x16 and 8x8 blocks to have early termination for RD computation of all possible modes. The early termination in intermode decision is performed by comparing the pixel values of current blocks and corresponding motion-compensated blocks. When the hypothesis tests are performed, the confidence intervals to accept the null hypothesis or not are decided according to the temporal scalability levels under the consideration of properties of hierarchical B-pictures. The proposed scheme exhibits effective early termination behavior in intermode decision of temporal scalabilities and leads to a significant reduction up to 69% in computational complexity with slight increment in bit amounts. The degradation of visual quality turns out to be negligible in terms of PSNR values.
This paper presents a new approach to translation and rotation invariant texture feature extraction for image texture retrieval. For the rotation invariant feature extraction, we invent angular projection along angular frequency in Polar coordinate system. The translation and rotation invariant feature vector for representing texture images is constructed by the averaged magnitude and the standard deviations of the magnitude of the Fourier transform spectrum obtained by the proposed angular projection. In order to easily implement the angular projection, the Radon transform is employed to obtain the Fourier transform spectrum of images in the Polar coordinate system. Then, angular projection is applied to extract the feature vector. We present our experimental results to show the robustness against the image rotation and the discriminatory capability for different texture images using MPEG-7 data set. Our Experiment result shows that the proposed rotation and translation invariant feature vector is effective in retrieval performance for the texture images with homogeneous, isotropic and local directionality.